Carrier Recombination and Diffusion in Wet-Cast Tin Iodide Perovskite Layers Under High Intensity Photoexcitation

Tin iodide perovskite CH3NH3SnI3 is often considered as a replacement for toxic lead halide perovskites. Tin iodide is not only suitable for production of solar cells, but also it emits in the near-infrared spectral region, which is unique among the metal halide perovskites. On the downside, the CH3NH3SnI3 layers tend to be of high unintentional p-type doping, which significantly limits the solar cell efficiency. On the other hand, it is little known how this doping could affect other optical and electrical properties important for light-emitting applications. Here, we present an optical study of carrier diffusion and recombination pathways by time-resolved photoluminescence, differential transmission, and light induced transient grating techniques at excitations close to the lasing regime. We investigate several CH3NH3SnI3 layers formed by a solvent bathing method and using different antisolvents, causing different structural quality and doping level of the layers. We observe the amplified spontaneous em...